Quartz oscillator arrangement



April 9, 1935. R. BECHMANN QUARTZ OSCILLATOR ARRANGEMENT Filed April 14,1932 INVENTOR RUDOLF BFCHMANN BY I Mm,

ATTORNEY Patented Apr. 9, 1935 1,996,737 QUARTZ osornm'roa manoarmn'rRudolf Bechmann, Berlin, Germany, assignor to Telefunken Gesellschaftfiir Drahtlose Telegraphic in. b. 11., Berlin, Germanma corporation ofGermany PATENT I OFFICE Application April 14, 1932. Serial No. 605.2245"In Germany April 14,1931

7 Claim This invention relates to a quartz crystal oscillatorarrangement particularly to the type in which the crystal and itsassociated electrodes are enclosed within a glass vessel. An object ofthis invention is tosimplify and improve .quartz crystal holders of theenclosedtype. This invention will best be understood by the followingspecification and accompanying drawing. In the drawing Fig. 1illustrates the general circuit arrangement of the crystal oscillator,Fig. 2 is a sectional view of the improved quartz crystal holder and itsglass envelope. Referring now to the circuit scheme most widely used forquartz oscillators is as shown in Figure 1, where l denotes the crystalholder the quartz crystal being interposed between two parallelelectrodes, 2 the grid leak (resistance) connected in parallel to them,3 the amplifier tube required to maintain the oscillations, and l achoke-coilconnected in the plate circuit thereof. It has been found tobe of advantage with aview to maintain constancy or stability not totune the said choke-coil by a condenser, in which case the dimensionthereof is but immaterial as regards its influence upon thespontaneously arising frequency of the arrangement.

It is known to be necessary in the prior art that the quartz crystalshould be confined within a temperature regulating container(thermostat) in order that the wave length may remain unafiected byfluctuations of the ambient temperature. 0n the other hand, it is known,however, that such intended frequency variations or changes as maybecome necessary in the operation of radio transmission systems can beproduced by controlled variation of the temperature of the quartzcrystal oscillator. For this purpose it is necessary to use a thermostatof very small thermal inertia in order that the intended frequencyvariations may be occasioned with adequate speed. As a result, also theheating time of the thermostat will be reducedin the desired manner to amarked degree. The invention hereinafter to be disclosed has for itspurpose to satisfy the said requirements.

According to the present invention the geometric dimensions and the heatcapacity of the thermostat are reduced to the minimum. Furthermore, thecrystal oscillator conjointly with such means as are used and providedfor temperature regulation are accommodated inside a 'more or lessperfectly evacuated container in order that the heat losses and thus theheating energy may be minimized.

One embodiment of the basic idea of the invention is shown in Figure 2.The piezo-electric quartz crystal II bears upon a metallic body I2 whichconstitutes one electrode of the crystal and its circuit. Thecooperating electrode I3 is placed, for instance, by the aid of a glassring l4 so as to insure the desired distance and is supported, e. g., bythe aid of a spring 5. The heating of the quartz crystal is effected bya windin 6 which is made from resistor wire. The temperature of thedevice may be regulated and controlled by various auxiliaries. For thearrangement hereinbefore disclosed there is particularly suited for thispurpose a measuring winding 1 which consists of a wire of a hightemperature coefilcient, such asv copper. This measuring winding in wellknown manner may be included in one arm of a Wheatstone bridgearrangement which, when the desired or intended temperature is reachedor prevails is in a state of equilibrium, whereas when the normaltemperature is exceeded a heating current of suitable value is released(caused to act) in the heating winding, though it will be understoodthat for the control of the heating also another thermal contact elementor means such as a bimetal strip or breaker may be used.

The construction elements hereinbefore mentioned are preferablyaccommodated inside a glass vessel so that the assembly has theappearance approximately of an amplifier tube.

I claim:

1. A piezo-electric crystal holder comprising a base having connectionpins and a sealed evacuated vessel above said base, an electrode supported above said base, an insulated ring secured to the upper portionof said electrode, a piezoelectric crystal resting on said electrode, asecond electrode spaced by said insulated ring and disposed above thesaid crystal, and a heating resistance surrounding said first mentionedelectrode for controlling the temperature of said crystal.

2. A piezo-electric crystal holder comprising a base having connectionpins, a sealed evacuated vessel above said base, an upper electrode, alower electrode supported by a central stud, a piezoelectric crystalresting on said electrode, an insulating ring enclosing said crystal andspacing it from said upper electrode, and a heating resistancesurrounding said lower electrode for controlling the temperature of saidcrystal.

3. A piezo-electric crystal holder comprising a base having connectionpins, a sealed evacuated vessel above said base, an upper electrode, alower circular electrode supported by a central stud, a

piezo-electric crystal resting on said electrode, an insulating ringenclosing said crystal and spacing it from said upper electrode, and aheating resistance surrounding said lower electrode for controlling thetemperature of said crystal.

4. A piezo-electric crystal holder comprising a base having connectionpinsa sealed evacuated vessel above'said base, an upper electrode, alower circular electrode supported by a central stud, a piezo-electriccrystal resting on said electrode, an insulating ring enclosing saidcrystal and spacing it from said upperelectrode, and a plurality ofwindings wound. aroundisaid lower electrode for controlling thetemperature of said crystal.

5 A piezo-electric crystal holder comprising a base having connectionpins," 5 sealedleivacuated vessel above said base, an upper electrodehaving a concaved recess, a lower circular electrode sup ported by acentral stud,,a .piezo-electric crystal resting on saidelectro'de, aninsulating ring'enclosing said crystal and spacing it from said upperelectrode,- and a spring co-operating with the concavedirecess on saidupper electrode and two vertical retaining membersflfor'securing' theen; tire electrode assemblage to said base, and a heating resistancesurrounding said lower electrode r, pe r. electrode, and a springco-operating with the concaved recess on said upper electrode and twovertical retaining members for securing the entire electrode assemblageto said base, and a heating winding and a measuring windingsurrounding-said lower electrode for controlling the temperature lofsaid crystal.

7. A piezo-electric crystal holder comprising a base having connectionpins and a sealed evacuated glass vessel above said base, an electrodesupported above said base, a glass ring secured to the upper portion ofsaid electrode, a piezoelectric crystal resting on said electrode, asec-,- ond electrode spaced by said glass ring and dis-e posed above thesaid crystaL'and a heatingre si'stance surrounding 'said'first mentionedelec- 'trode, for controllingthe temperature of said crystal. i

